Set in 1929, Greenwood’s lighthearted 20th Phryne Fisher mystery (after 2013’s Unnatural Habits) opens with news of a highly unusual murder. Hedley Tregennis, the conductor of the Melbourne (Australia) Harmony Choir, with the Occasional Orchestra, received a fatal dose of morphine before someone stuffed sheet music from Mendelssohn’s oratorio Elijah down his throat. Insp. Jack Robinson, on the pretext that he doesn’t know anything about music or “these sort of people,” easily persuades PI Phryne to investigate. The unflappable flapper soon ascertains that not everyone is saddened by the demise of the lecherous Tregennis. At the same time, Phryne, who spied for the British during WWI, attempts to thwart an attempt on the life of former code breaker Rupert Sheffield, who’s also an expert mathematician. The usual mix of fair-play clues and romantic escapades for Phryne helps keep this 25-year-old series fresh. (May)